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The effect of microstructure refinement on magnetic properties in single-phase Ll0 Fe58Pt42 films was studied. Samples with thickness t of 100, 200, and 300 nm were sputtering deposited on glass substrate with elevated temperatures Ta of 400 and 800 °C. In the t=300 series of films, the order parameter of films with Ta=400 and 800 °C were identical, about 0.663, but the average grain size is different by approximately eight times in diameter (from ∼75 to ∼610 nm). Comparing to the film of Ta=800 °C with large grains, significant enhancement in remanence of about 32% was obtained in the 400 °C annealed film (∼880 emu/cm3) and the energy density was achieved an increment of about 72% (19.6 MG Oe), which exceeds the theoretical preditions. The reasonable explanations are summarized as the dimension confinement of interactions and the degradation of anisotropy. [ABSTRACT FROM AUTHOR]

Magnetic domain configurations of microstructured permalloy exchange coupled by an antiferromagnetic (NiO) thin film is presented. NiO/NiFe bilayer micrometer array elements were fabricated using electron beam lithography through a lift-off technique. The magnetic force microscopy images of the elliptical and rectangular elements with various aspect ratios showed dipole-like magnetic domain structures. The bright/dark arc contrast associated with the magnetic pole strength was dependent on the anisotropic exchange field. Furthermore, the shape anisotropy can overwhelm anisotropic exchange in patterned elements with a high aspect ratio and thicker permalloy film. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

InGaN-based nanorods with a rod density of ∼3.0×1010 cm-2 were fabricated from a light-emitting diode structure by an inductively coupled plasma dry-etching with nanoscale nickel metal islands. The nanoscale nickel metal islands were formed from a Ni film by a rapid thermal annealing at 850 °C for 1 min. The influence of thicknesses of Ni metal film on the diameter and density of nanorods was also investigated. Structural and optical properties of the InGaN-based nanorods were studied with field-emission scanning electron microscopy, transmission electron microscopy, and photoluminescence. The diameters and heights of nanorods were estimated to be 60–100 nm and more than 0.28 μm, respectively. The emission-peak wavelength of nanorods showed a blueshift of 5.1 nm from that of the bulk structure. An enhancement by a factor of five times in photoluminescence intensity of nanorods compared to that of the bulk structure was also observed in this work. The blueshift is attributed to the strain relaxation in the well, quantum-confinement effect, or a combination of the two, which result in the enhancement in emission intensity. [ABSTRACT FROM AUTHOR]

High density magnesium (Mg)-doped gallium nitride (GaN) nanorods were fabricated by inductively coupled plasma reactive ion etching technique from the epitaxial film. Under the fixed Cl2/Ar flow rate of 10/25 SCCM (SCCM denotes cubic centimeter per minute at STP) and inductively coupled plasma/bias power of 200/200 W, the nanorods were fabricated with a density of 108–1010 cm2 and dimension of 20–100 nm by varying the chamber pressure from 10 to 30 mTorr. A large blueshift was observed in the photoluminescence (PL) peak energy of Mg-doped GaN nanorods under HeCd laser (325 nm) excitation. The PL spectra of nanorods show a typical donor-acceptor-pair emission around 3.0 eV with a large blueshift compared to the Mg-doped GaN film. The blueshift energy increases from 8 to 67 meV as the excitation intensity varies from 12 to 56 kW/cm2. Possible reasons causing the power dependence of spectral shift in the PL emission energy are discussed. [ABSTRACT FROM AUTHOR]

Initial stress (σi) of a room-temperature deposited FePt films was manipulated to study the order-disorder transformation. We observed that, while σi was increased from -1.01 (compressive) to 0.18 GPa (tensile), the phase transformation activation energy decreased from 0.387 to 0.23 eV/atom. This causes a reduction in ordering temperature of about 100 °C. We also found that densification induces an increase in tensile stress of about 1 GPa before ordering. In the films with small σi, strong tension facilitates the nucleation of L10 FePt; however, if highly compressive σi cancels the densification tension, ordering is retarded causing higher ordering temperature. [ABSTRACT FROM AUTHOR]

GaN-based vertical-cavity surface emitting laser with 3 λ cavity and hybrid mirrors, consisting of the 25 pairs AlN/GaN dielectric Bragg reflector and the 8 pairs Ta2O5/SiO2, was fabricated. The laser action was achieved under the optical pumping at room temperature with a threshold pumping energy density of about 53 mJ/cm2. The laser emits 448 nm blue wavelength with a linewidth of 0.25 nm and the laser beam has a degree of polarization of about 84%. [ABSTRACT FROM AUTHOR]